Table of Content

30 November 1984, Volume 2 Issue 4

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STUDIES ON MALARIA SURVEILLANCE METHODS IN THE FINAL STAGE OF MALARIA ERADICATION IN KAILI COUNTY, GUIZHOU

1984, 2(4):  209-211. 

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Kaili county is situated in the middle of Guizhou, with an area of 1, 400km2, and a population of 310,000.In 1957, the malarial morbidity was 944 per ten thousand, and the parasite rate was 1,120 per ten thousand. The programme of malaria control has been 玜jrried out in large scale since 1958 and the morbidity and parasite rates dropped down in 1965 to 1 and 3 per ten thousand, respectively. Since 1977 the malaria administration and surveillance in the final stage of malaria eradication have been undertaken all over the county. At present, the leading groups of malaria,control-at conuty, district and commune levels are well established. Health bureau and the. .antiepidemic station of the county, the district hospital and commune health station are responsible formalaria surveillance within the area confined. The system of malaria case detection, presumptive treatment, radical treatment, follow-up; of malaria case/foci are set up. From 1980 to 1982, the annual blood examination rate was above 10% every,year, The annual parasite incidence was between 0.5-0.06 per ten thousand.

THE EFFECT OF ANTIMALARIA MEASURES OVER TWENTY YEARS AND THE CURRENT EPIDEMIC STATUS IN GUANGXI

1984, 2(4):  212-215. 

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This paper outlines the history of malaria control in Guangxi Autonomous Region over the past 20 years and gives an account of current epidemic status.High incidence of malaria was restricted in hilly areas and Anopheles minimus was the main vector.Following annual malaria control measures including residual spraying, the incidence of three kifrds of malaria was progressively reduced, the total morbidity of malaria in the region being 3.4 per ten thousand. Qudrtan malaria was rarely seen, and the area epidemic to falciparum malaria was sharply reduced. Howevery in the residual foci of falcipawm malaria, chloroquine-resistant cases are now emergingi Stress should be put on the detection of new cases and the radical treatment. Indoor residual spray must be carried out and chloroquine-resistant malaria must be effectively controlled in the highly epidemic areas.

THE ROLE OF ANOPHELES LESTERI ANTHROPOPHAGUS IN MALARIA TRANSMISSION IN JIANGHUAI REGION, ANHUI

1984, 2(4):  216-219. 

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In order to further clarify the role of A. lesteri anthropophagus in malaria transmission in Jianghuai Region, Huangbo and Duci brigades of Luzhen Commune of suchen County, Anhui Province were selected for investigation from July to September,. 1982.The malaria morbidity rates of Huangbo and Duci brigades were 13.2%(P.falciparum 7.9%) and 5.0% (P. falciparum 1.6%); the parasite rates of local inhabitants were 37.8% (P. falciparum 16.5%) and 14.6% (P. falciparum 1.4%) respectively. Of 11,290 anophelines captured from bed-nets of dwellings in these two brigades, A. lesteri anthropophagus was predominant in Huangbo brigade (69.7% of total anpheline population) while in Duci brigade A. sinensis was predominant (89.2%). The positive sporozoite rates of A. lesteri anthropophagus and A. sinensis were 1.58% (53/3,357) and 0.11% (4/3,666), respectively.The entomological inoculation rate of the former was markedly higher than that of the latter. The local A. lesteri anthropophagus and A. sinensis and the local P. falciparum from gametocyte-positive blood samples were used for artificial infection. The positive rates of oocysts and sporozoites in A. lesteri anthropophagus were 27.9% and 10.9% (44/402), while those in A. sineresis, 11.3% and 3.0% (20/662) respectively.The results demonstrated that A. lesteri anthropophagus is the principal vector in Jianghuai Region of Anhui Province and plays a more important role in the transmission of P. falciparum than A. sinensis.WHO Collaborating Center for Malaria, Schistosomiasis and Filariasis. Partial financial support was received from UNDP/World Bank/WHO TDR

STUDIES ON DDT RESIDUAL SPRAYING FOR CONTROLLING ANOPHELES LESTERI ANTHROPOPHAGUS AND PLASMODIUM FALCIPARUM MALARIA

1984, 2(4):  220-223. 

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This article reports on the result of DDT house residual spraying in the control of A. lesleri anthropophagus and falciparum malaria in Luzhen Commune, Shucheng County, from June to July, 1983. The DDT house residual spraying has good preventive effect on A. lesleri anthropophagus, the biting rate decreased by 99.5% and the life span by 33.5%. But it is not so good for A. hyrcanus var sinensis Wied and its relative density index is higher, i.e. above 100.The transmission rate for malaria in the pilot area in 1983 has obviously decreased, especially for falciparum malaria which has decreased over 85%. This proves that DDT house residual spraying combined with case treatment in an area where A. lesleri anthropophagus is the chief vector is effective in controlling the transmission of falciparum malaria.

RELAPSES AND INDIRECT FLUORESCENT ANTIBODY LEVEL IN VIVAX MALARIA PATIENTS AFTER CHLOROQUINE AND CHLOROQUINE-PRIMAQUINE TREATMENT

1984, 2(4):  224-227. 

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82 and 145 patients of vivax malaria were treated with chloroquine alone (1,500mg for three days) and in combination with primaquine 22.5mg for 5 days respectively from October to November 1980 and followed up till July 1981 in Huanghuai Plain. The relapse rates were 45.1% and 15.2% and the average number of relapses of the patients were 1.4 and 1.1 respectively. All patients with more than one post-treatment relapse were children. No recrudescence within eight weeks was noted in either group. Most relapses occurred in May and June.The IFA test carried out in July 1981 revealed that the difference in the positive rates (≥1:80) .the total geometric mean reciprocal litres and the re-rising rates of antibody titre between the two groups were significant. These coincided with the parasitological relapse rates examined by microscopy simultaneously. It appears that IFA test may be useful in comparing the efficacy of different regimens in the treatment of tertian malaria.

OBSERVATIONS ON CRITERIA OF OVARIAN DIAPAUSE IN CVLEX PIPIENS PALLENS AND ITS HORMONE CONTROL

1984, 2(4):  228-231. 

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By comparative studies of the follicle development and mosquito diapause, the major criterion of diapause in adult C, pipiens pallens has been demonstrated to be the retardation of the first follicle at N-stage, which occurred 24 hours after emergence, with a length around 50 micrometers. The almost equal length of the first follicle and the germarium (i.e. second follicle plus third follicle) may also be considered as a secondary evidence of the diapause. Developing mosquitoes are indicated by the appearance of la stage which is the most prosperous period of the follicle development in its early stage when the mosquitoes start blood-feeding. In the absence of blood supply; development may continue up to and then stop at the resting stage of IIb.The process of follicle development in diapaused adults was carefully compared with that of decapitated individuals which were taken as an alternative of brain inhibition to juvenile hormone (JH) secretions of the corpora allata (CA). Results strongly inferred that follicle retardation may be attributed to lack of JH. It is suggested that the develpment of the first follicle from stage No.1 at emergence to N-stage may be unrelated to JH, while further development from N-stage may depend on the function of JH from CA. The critical point of JH secretion from CA was demonstrated at around 24 hours after emergence of the female adult.

RESIDUAL BLOOD SCHIZONTOCIDAL ACTIVITY OF PYRONARIDINE AGAINST RODENT MALARIA

1984, 2(4):  232-233. 

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The mice were administered ig or im with 100mg base/kg pyronaridine 15 days before (D-15) ip inoculation (D0) of Plasmodium yoelii-infected erythrocytes, and parasitemia did not occur in most of the drugged mice on D6 and D10. Similar results were obtained, with 10mg base/kg of pyronaridine given ig or im on D_10, 5mg/kg im on D_6 and 5mg/kg ig on D_4. Nevertheless, a dose of 400mg base/kg of chloroquine given either ig or im on D_3 failed to protect mice from P. yoelii infection, since the P. yoelii strain 265 used in the experiment had a low level of innate resistance to chloroquine.It was revealed in the expertments with P. berghei that the duration of schizonto-cidal effect of pyronaridine was markedly longer than that of chloroquine. A. dose of 10mg/kg pyronaridine ( 1.47 times ED50, or 0.7% LD50) given on D_6 exerted apparently suppressive action on blood schizonts, while an equivalent dose of 67mg/kg chloroquine (1.47 times ED50, or 10% LD50) showed slightly suppressive activity only when the drug was administered on D-2.

STUDIES ON THE BIOLOGICAL CHARACTERISTICS AND THE STRAIN-TYPE OF PLASMODIVM CYNOMOLGIMAI NTAINED IN CHINA

1984, 2(4):  234-237. 

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Exoerythrocytic stage: On the 7th day after sporozoite inoculation, intact crypto-zoites generally appear irregularly in outline; some of them may be lobed and some may contain 1-4 vacuoles 4-6μm in diameter; their peripheral nuclei arrange at random, maturing at the 8th day. Parasitemia may appear by the end of the 8th day. The relapse rate of this parasite in Macaca mulatta is about 62.5%.Blood stage: The parasites prefer to invade the 4th stage reticulocytes. Trophozoite--induced infections could be maintained for over 7 years.Sporogony: It takes place in Anopheles dims, A. stephensi and A. lesteri, the first two species being more susceptible than the last one. Oocysts are round or elliptical in shape, they measure 35±5.2μm in diameter at the 8th day and 60μm at the maxi-mum; sporozoites can be found in the salivary glands at the 8th day.Based on the findings mentioned above, this malaria parasite may be considered as the Cambodian strain of Plasmodium cynomolgi.

EXPERIMENTAL STUDIES ON THE PERIODICAL VIABILITY OF GAMETOCYTES OF PLASMODIUM VIVAX

1984, 2(4):  238-242. 

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Anopheles sinensis were fed through membrane on blood from five patients naturally infected with vivax malaria in the southern pfert of Yunnan Province. After feeding at 8-hour intervals for 48 hours., all unfed mo'squitoes were removed from cages and the engorged ones were incubated at 26±1℃ and 70-80% RH on 10% glucose. 13 to 100 mosquitoes from each batch were dissected according to the level of infection 6-7 days later and the number of oocysts were recorded. The percentage of mosquitoes infected and the mean number of oocysts per infected gut were taken as critaria of the viability of the gametocytes. Both thick and thin, blood films were taken at the time when mosquitoes fed, and the number of asexual parasites and gametocytes were counted by the routine method.The general conclusions drawn from our work are: (1) The viability period of the gametocytes was demonstrated, but the nocturnal periodicity of morphologically mature gametocytes, as previously noted by Hawking et al., was not regularly observed. It is doubtful whether Hawking's work on monkey infections could be applied to human Plasmodium vivax. (2) There is no marked and definite correlation between the infecti-vity of mosquitoes and the total parasite count or gametocyte density. (3) The infectivity of gametocytes for mosquitoes reached a peak at the interschizogony period and fell to low level at the time when schizogony occurred. (4) The time required for the rise and decline of gametocyte viability is little longer than the time required for an schizogony cycle.

PRELIMINARY OBSERVATION ON THE PRE-ERYTHROCYTIC SCHIZONT OF PLASMODIVM BERGHEI ANKA STRAIN

1984, 2(4):  243-244. 

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Mice (C57BL, ICR/JCL and Kunming strain) and rats were infected by intravenous inoculation of sporozoites of Plasmodium berghei ANKA strain via tail vein. The pre-erythrocytic schizonts were found in hepatocytes 46 to 47 hrs after injection. They were usually spherical, sometimes a little oval, in shape and the mean size was 8.07×16.13-25.80 ×30.54μm. It seemed clear that the number of pre-erythrocytic schizonts was larger in rats than in mice.

PURINE METABOLISM IN SCHISTOSOMA JAPONICUM

1984, 2(4):  245-248. 

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Adult Schistosoma japonicum were found to contain a spectrum of purine bases; nucleosides and nucleotides including ATP, ADP, AMP, uridine, hypoxanthine, inosine, adenosine, adenine and GTP. ATP was rapidly converted to hypoxanthine by S. japonicum hoinogenates.The adenosine phosphorylase activity of S. japonicum was 27.3μmole/min/worm pair. This enzyme was released into the culture medium when the worms were incubated in vitro for 24 hours. Pyquiton(8 × 10-4M) and formycin A (1.6×10-3M) inhibited this, enzyme 58% and 72%, respectively.The ATPase activity of the tegument of male and female S. japonicum was found to be 17.313.8 and 17.0±2.5μmole Pi/hr/mg protein. In the presence of 3mM Mg2+, this enzyme was not activated by Na+ (100mM) and K+ (20mM), nor inhibited by ouabain (5×10-4M), suggesting that Na+-K+-activated ATPase might be absent in the tegument. This enzyme was isolated and purified by PAGE and isoelectric focusing and its Michaelis constant before and after purification was estimated.

PARASITISM OF HUMAN HAIR FOLLICLE MITES AND ITS RELATION TO THE HISTOPATHOLOGY OF ROSACEA

1984, 2(4):  249-252. 

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Basing upon histopathological studies of 21 cases of rosacea, the relation between mite infection and pathological changes in the parasitized tissues was correlated.Many mites were found in the dilated hair follicles or proliferative sebaceous glands, particularly in lesions associated with varying grades of inflammatory reaction. Results showed that the histopathological changes are intimately in correlation with the infection of two species of human hair follicles mites in patients of 3 forms of rosacea. These suggest that human hair follicle mites are pathogenic, and can be the important causative agents of dermatitis form of rosacea. Both species of mites (Demodex folliculorum and Demodex brevis) are related to the etiolology of acne and rhinophyma forms of rosacea. It gives support to the clinical diagnosis and treatment of rosacea.

STUDIES ON THE ANIMAL MODEL OF TRICHOMONAS VAGINALIS

1984, 2(4):  253-256. 

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Four strains of Trichomonas vaginalis were isolated from patients with different severity of symptomatology. Strains A and B produced marked symptoms in patients, strain C produced less symptoms, while strain D was isolated from carrier without symptoms. Mice- were inoculated by different routes with axenic cultures of the 4 strains of T. vaginalis, and their pathogenicity to mice were studied.All the 4 strains can induce abscess in mice. By intraperitoneal route, strains A ahd D are most pathogenic, followed by strain B and strain C, as judged from the extent of abscess formation as well as mortality rate in mice. By subcutaneous inoculation, the virulence of strains A and B is stronger than that of strains C and D, as estimated by the area of abscess produced. Subcutaneous inoculation of T. vaginalis into mice can be used as a method to estimate the virulence of various strains in human host. The size of abscess formed was found to be related to the number of protozoa inoculated.Histological sections of parasitic abscess in liver showed that it was well circumscribed, its external border was densely packed with a layer of T. vaginalis, with long axis perpendicular to the border of the abscess. Liver cells in contact with the parasitds in the border area usually showed hyaline change. Inside the abscess, necrotic liver tissues and scattered T. vaginalis could be found. Localized infiltration of mono-nuclear and polymorphic leucocytes could be seen at the border area and around the remaining portal areas in the abscess.

EXPERIMENTAL STUDY ON CELLULOSE ACETATE DIFFUSION METHOD FOR THE IDENTIFICATION OF MOSQUITO BLOOD MEALS

1984, 2(4):  257-259. 

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This paper reports on the results of application of the cellulose acetate micro immunodiffusion to identify the host source of anopheline mosquito blood meals. For comparison, the precipitin test was done simultaneously.129 specimens of the 2-3 stage of anopheline mosquito blood meals were identified by cellulose acetate diffusion test and precipitin test, the positive rates being 98.4% and 89.9% respectively. For 121 specimens from the 4-5 stage of mosquito blood meals, the postivity were 93.4% and 19.8% respectively. When tested against 102 specimens of mosquito blood meals collected from cowsheds and pig fences, the former technique showed 100% specificity while the latter only 83.3%. The results indicated that the cellulose acetate diffusion test is more sensitive and specific thap the precipitin test. In addition, the method is also rapid and simple for identifying mosquito blood meals.

THE RADICAL EFFICACY OF PYRONARIDINE-PRIMAQUINE COMBINATION IN TERTIAN MALARIA

1984, 2(4):  260-262. 

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The authors adopted a three-day pyronaridine-primaquine combination regimen in treating 656 patients (395 male, 261 female) with tertian malaria in 1976. The patients were divided into three groups. Group A: the total dosage of pyronaridine was 32mg/kg body weight (1.6g per adult), 0.8g for the first day and 0.4g for the second and the third day each; primaquine 30mg q.d. for three days. Group B: the total dosage of pyronaridine was 1.2g, 0.4g q.d. for three days; primaquine 30mg q.d. for three days. Control group: 126 patients treated with a total dosage of chloroqume 1.2g(0.6g for the 1st day, 0.3g for the 2nd and the 3rd day each) and primaquine 22.5mg q.d. for 8 days with a total dosage of 180mg. 100% immediate cure was observed in all the 3 groups and the relapse rate in groups A, B and C was 2.0%, 3.5% and 0.8%, respectively. On the whole, the three-day pyronaridine-primaquine regimen was found to have the following advantages: 1. rapid elimination of malaria parasites-48 hrs for the asexual and 72 hrs for the sexual forms; 2. rapid control of symptoms; 3. high rate of radical cure; 4. shorter term of treatment; 5. less dosage of primaquine.

OBSERVATION ON THE EEFFICACY OF PYRONARIDINE INVIVAX MALARIA

1984, 2(4):  263-264. 

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37 patients in Qionglai County, Sichuan Province suffered from acute vivax malaria were treated with pyronaridine phosphate. A total of 1.2 g (base) was administered in 4 divided doses i.e. 0.3 g initially, repeatedly 6-8 hours later and once daily in the following 2 days. Twenty acute vivax malaria patients in the same district were treated with chloroquine phosphate in similar dose schedule as control.All the patients treated with pyronaridine phosphate became free from parasite in an average of 59.3 hours and free from fever in 25.5 hours, while patients treated with chloroquine in 60 hrs and 28.1 hrs. Two patients treated with pyronaridine phosphate and one patient with chloroquine had relapse of parasitaemia 30 days later.No significant side-effects were observed in both groups.